Thread: iMac?

BSD is a Unix operating system

AT&T's research division, Bell Labs, developed UNIX in 1969
UNIX was a research operating system, intended to drive innovation

AT&T licensed copies of UNIX to people
When you bought a UNIX license, you got the complete source code to the operating system, and full rights to use, modify the code and redistribute

The University of California, Berkeley bought a UNIX license
they then went about modifying it to suit their needs

They invented the Unix domain sockets (called Berkeley sockets, at the time), the TCP/IP stack, the init runlevel system, and a whole host of other things to enhance the operating system in a fully networked, multi-user environment

BSD is Unix
AIX is Unix
HP-UX is Unix
Solaris is Unix
Xenix is Unix

BSD was an original Unix derivative

Since BSD, and the other Unix derivatives mentioned above, first arrived, a few things have happened

- AT&T sold the rights of UNIX to the Santa Cruz Operation
- The Santa Cruz Operation then sold the rights to UNIX to Novell
- Novell then gave up the rights to UNIX, and transfered all rights & ownership over to the Open Group

With the UNIX rights and ownership now held by a non-profit organisation, UNIX is now open to other non-profit organisations and individuals
(no more licensing)

Free BSD, Open BSD & Net BSD are derived (at varying points) from BSD

The Mac OS X userland is lifted straight from Free BSD
The Mac OS X kernel is the Free BSD kernel (with a few bits & bobs added by Apple)

This is Linux focused, rather than OS X focused (because I wrote it for a different purpose)

but here's a brief overview of Unix's history

In 1964, AT&T embarked on an ambitious project to create an operating system to control and automate their telephone network
While electronic switch boards were not rare at the time, such systems were entirely bespoke and required extensive reworking for any alterations or changes to the network topology.

AT&T envisioned a programmable interface that would allow them to alter the underlying network without needing to re-wire the circuit relays controlling the network
This project was called Multics, and was developed by AT&T's research division, Bell Labs

It is important to note that before this, there wasn't really any such thing as an operating system. General Motors had a fleet of programmable computers to control it's production lines, but the instructions were all written by hand to directly control the various hardware robotics, the control system simply automated the execution process. This meant that changes to the underlying role, structure or purpose of the systems, including any computer hardware changes, were very difficult to accomplish. “porting” such control programs to different hardware was nigh impossible, often times requiring a total system rewrite

For their telephone network, AT&T attempted to write a platform on top of which programs would execute
Infrastructure changes would require porting the platform
Porting the platform would bring all the programs and business logic along with it, eliminating the need to re-write hundreds (or even thousands) of individual control programs

They developed a programming language, called B (short for Bell)
The language was designed to abstract out the low-level machine instructions, instead presenting a unified interface to write programs from a higher level
B was also designed for easy porting across hardware

Multics, the world's first “modern” operating system, was written in pure assembly language
but all the programs that ran on top of the operating system, were written in B

Several of the developers at Bell labs felt that the Multics project took a few wrong turns
By all accounts, Multics was large, complicated and a nightmare to maintain
So when they were finished, Bell Labs went about developing what they considered the “right” way to develop an operating system – they named their project Unics

One of these “right ways” of doing things, was writing the operating system in a high level language - This had never been attempted before

Unics was written in B

B had a few shortcomings, so the language was redesigned
and called C (one up from B)

Unics was rewritten in C
also got a spelling change, to UNIX

UNIX was an operating system designed to be redesigned
by that, I mean it didn't try to do everything
instead it did the bare basics

The idea was simple, purchase a UNIX license from AT&T and you got the complete source code for UNIX – then you could customise and enhance the operating system to suit your needs
as I said, it was an operating system designed to be redesigned

Due to it's immense flexibility and modular design, UNIX was a big hit with large businesses
UNIX soon came to dominate the mainframe market, pushing out more expensive, bespoke systems

It's now the 80's, and out of AT&T's licensing of unix came numerous distributions of unix, the big ones being BSD (the UC Berkeley Software Distribution of Unix), AIX (developed by IBM), HP-UX (developed by Hewlett Packard), Solaris (developed by Sun Microsystems) and a whole host of others

The computer is fast becoming a necessary staple in every business environment, not just big businesses, due to smaller machine sizes, falling prices and success stories from early mainframe adopters
The idea of making serious money out of operating systems is realised by software companies.
due to this, a lot of companies began restricting source code level access to their operating systems in an attempt to protect their development and out-do the competition

Previously, people bought hardware
Hardware was what ultimately did the work. Hardware was tactile and easily quantifiable.
Software was a necessity to control the hardware
The idea of selling software was completely new territory

Richard Stallman saw this move to proprietary software as a bad thing, and launched the GNU project in 1983 – mission statement, to develop a unix-like operating system that maintained the once “free” nature of software

In addition to this, the increasingly proprietary nature of unix systems bred incompatibilities that seriously hampered progress
The incompatibilities between unix systems paved the way for Windows NT to stride in and take a chunk of market share (before the early 90's, Windows was a toy used only on cheap home machines by people who couldn't afford better systems)

In 1991, Linus Torvalds started work on Linux – a unix-like operating system kernel based heavily on Minix (one of the many unix variants)

Linus realised he'd bitten off more than he could chew, as developing a kernel (let alone a complete operating system) was too much for one man, so he released his kernel online and accepted the help of others

The GNU project saw an opportunity here
They'd succeeded in creating all the userland programs needed to make an operating system, but they lacked a kernel. So the GNU project selected Linux to be their kernel, and the GNU/Linux operating system was born

Operating systems are complex things, there is no “one size fits all”
(there's something like 3000 kernel options you need to deal with when compiling the Linux kernel, let alone any of the other necessary programs that make up an OS)
because of this, individual people building their own GNU/Linux operating system is not really feasible

So, mirroring what Unix had done many years previously, different distributions of GNU/Linux cropped up – each one catering to a different audience, each one having a different goal
The GNU General Public License (GPL) was instrumental in ensuring that these distributions remained open to all, and didn't fall into a pit of proprietary, incompatible mess that unix systems had

Many (many) Linux distros have come and gone, but a few have stuck around
Slackware, Debian and Redhat being the 3 big ones
but again, like unix before it, there's a whole heap of distributions, each aiming for a different goal

That's what I remember from learning about Unix. He's right DP.

Darwin is actually a modern variant of NEXTStep which was based on BSD Unix, but with a better integration of kernel and GUI.

An no Darwin is UNIX. Linux, is "unix-like."

Windows is an absolute disaster if you look at the specs of the kernel. There is a reason that *nix is the dominate operating system.

Originally Posted by ninja9578

Darwin is actually a modern variant of NEXTStep which was based on BSD Unix, but with a better integration of kernel and GUI.

An no Darwin is UNIX. Linux, is "unix-like."

Windows is an absolute disaster if you look at the specs of the kernel. There is a reason that *nix is the dominate operating system.

What do you mean by dominant? 1% marketshare?

I do agree that Linux distros are superior for some people's needs, but it will probably never be the year of the Linux desktop.

Linux market share in servers is approx 40%
Windows is also around 40% on servers
the rest is taken up by proprietary Unix

Originally Posted by Ynot

Linux market share in servers is approx 40%
Windows is also around 40% on servers
the rest is taken up by proprietary Unix

But that is only in servers. In general, the last records put Linux at around 1%, even Hackintoshes have a bigger market share, sadly.

Originally Posted by Demon Parasite

What do you mean by dominant? 1% marketshare?

I do agree that Linux distros are superior for some people's needs, but it will probably never be the year of the Linux desktop.

1% PC are Linux, 10% of PCs are OSX UNIX
40% of Servers are Linux, 40% are UNIX
95% of Cell phones are Linux
40% of smart phones are Linux, 30% are OSX
95% of embedded systems are Linux


*nix is the dominate operating system by a huge margin

Desktop computers aren't the majority of computers.

You know those scanners at Borders that let you listen to the CDs they have there?

Linux. I saw Tux flash by on the screen when it was booting up.